Although substantial efforts have been made to decrease interparticular spacings in NP solids, typically for enhanced conductivity, many optical phenomena such as plasmonic enhancement of photoluminescence have ideal interparticle separations greater than the 1-2 nm typically accessed with commercially available ligands, such as alkylthiols, ω-functionalized alkylthiols, etc. To date, lithographic methods have been used to study these effects, but recent approaches including DNA hybridization of NPs, liquid-crystals functionalization, liquid crystals defects and block copolymers surface templates, have been reported. Inter-particle spacings modulation in the range of 0.6-1.9 nm have been achieved in binary mixtures of poly(amidoamine) dendrimers (PAMAM, G0-G4) and mercaptoundecanoic acid passivated gold NPs prepared via co-precipitation, but without control of the ordering (see, for example, Srivastava, S.; Frankamp, B. L.; Rotello, V. M. Chem. Mater. 2005, 17, 487). In all cases, the distance modulation is presented in dimers, trimers, or in small particles clusters, and the accessible range is limited.
Studies of 2D arrays of iron oxide NPs, liquid-crystalline self-assemblies of dendronized gold nanoparticles (see, for example, Donnio, B.; Garcia-Vázquez, P.; Gallani, J. L.; Guillon, D.; Terazzi, E. Adv. Mater. 2007, 19, 3534; Kanie, K.; Matsubara, M.; Zeng, X.; Liu, F.; Ungar, G.; Nakamura, H.; Muramatsu, A. J. Am. Chem. Soc. 2012, 134, 808; and Mischler, S.; Guerra S.; Deschenaux. R. Chem. Commun. 2012, 48, 2183), construction of covalently bound dendrimer-NP multilayers, and the use of dendronized hybrid systems in drug delivery, imaging and theranostics, as well as recoverable catalysts, are also known.
Achieving interparticle distance control while still preserving ordered assemblies of NPs over large areas with high uniformity is an important and unresolved challenge that is inevitable for the fabrication of solid-state devices and metamaterials based on NPs. Herein, hybrid nanoparticles capable of interparticle distance control while still preserving ordered assemblies over large areas with high uniformity are described.